1. Field of the Invention
The present invention relates to an apparatus for detecting steering angle in a vehicle, and particularly to an apparatus for detecting steering angle in a vehicle using a magneto resistive sensor.
2. Description of the Related Art
Variety of apparatus for detecting rotational angle of a rotating body, is introduced, and these apparatus for detecting rotational angle could be used for the apparatus for detecting steering angle in a vehicle. More specifically, the apparatus for detecting steering angle is adopted for roll suppression upon steering in controlling attenuation force of shock absorber in the vehicle.
FIG. 1 is a plan view schematically illustrating the apparatus for detecting steering angle in vehicle of the related art, and FIG. 2 is a cross-sectional view taken along line A—A in the apparatus for detecting steering angle in vehicle of the related art. As shown in FIG. 1, the mechanical construction for the apparatus for detecting steering angle in vehicle of a related art, may includes a housing 80 for receiving the apparatus; a shaft gear 50 axially combined to a steering shaft 40 of a vehicle; a first detecting gear 52 joined in a tooth combining manner, with a predetermined gear ratio, to appropriate position of the shaft gear 50; a first permanent magnet 56 installed on an axis of the first detecting gear 52, for generating rotational magnetic field; a first magneto resistive sensor 20 closely installed on an upper portion of the first permanent magnet 56, for detecting rotational angle of the rotational magnetic field; a second detecting gear 58 joined in a tooth combining manner, with a predetermined gear ratio, to appropriate position of the shaft gear 50 on the same plane of the first detecting gear 52; a second permanent magnet 60 installed on an axis of the second detecting gear 58, for generating rotational magnetic field; a second magneto resistive sensor 30 closely installed on an upper portion of the second permanent magnet 60, for detecting rotational angle of the rotational magnetic field; a printed circuit board 70 on which other electrical circuits necessary for the detecting apparatus are mounted, for supporting the first and the second magneto resistive sensors 20 and 30; and a housing 80 within which the above parts are included.
In the foregoing construction, the shaft gear 50, the first detecting gear 52 and the second detecting gear 58 are all realized by a spur gear, and the number of teeth for the shaft gear is 42, the number of teeth for the first detecting gear 52 is 28, and the number of teeth for the second detecting gear 58 is 26. Therefore, a gear ratio between the shaft gear 50 and the first detecting gear 52 is 42/28, and a gear ratio between the shaft gear 50 and the second detecting gear 58 is 42/26. In the meantime, as the steering shaft 40, that is to say, the shaft gear 50 rotates, the permanent magnets 56 and 60 respectively installed on axes of the first detecting gear 52 and the second detecting gear 58, rotate together with the first and the second detecting gears 52 and 58, whereby directions of magnetic fields are changed. The first and the second magneto resistive sensors 20 and 30 output detecting signals in response to such changes, and computing/controlling unit (not shown) outputs steering angle and direction by processing the detected signals using a predetermined program.
But, according to the apparatus for detecting steering angle in vehicle of the related art, as the first and the second detecting gears are joined each other in a tooth combining manner on the same plane, a problem that the whole size for the detecting apparatus becomes large, is generated.